Iowa Code § 691.3
The commissioner of public safety shall make rules defining the capabilities of the criminalistics laboratory. The commissioner shall make rules governing the handling of items to be processed by the criminalistics laboratory from the time they are forwarded to the laboratory by a county medical examiner or a city or state law enforcement agency or county sheriff until their return to the forwarder. The rules shall prescribe a method of identifying, forwarding, handling and returning items that will maintain the identity and integrity of the item. An item handled in conformity with the rules shall be presumed to be admissible in evidence as to the period in transit to and from and while in custody of the laboratory without further foundation.
Iowa Code § 691.3